Revisiting the Posttherapeutic Cure Criterion in Chagas Disease: Time for New Methods, More Questions, Doubts, and Polemics or Time to Change Old Concepts?

Table 2

Categories of laboratorial methods and targets available for evaluation of the etiological treatment efficacy/benefits and their interpretation in the context of Chagas disease cure assessment.

Category	Laboratorial method	Target	Results	Interpretation
Conventional serological tests	CFR, IHA, IIF, and ELISA	Fixed epimastigotes; Recombinant antigens	POS	Therapeutic failure; (Classic criterion)
			NEG	Cured; (Both criteria)
Nonconventional; serological tests	ML; FC-ALTA, FC-AFEA, and FC-ATE	Live trypomastigotes; Live amastigotes	POS	Therapeutic failure; (Krettli and Brener criterion)
			NEG	Cured; (Krettli and Brener criterion)
Direct; parasitological tests	FBE, trypomastigote concentration; (buffy coat, microhematocrit, and Strout tests)	Blood trypomastigotes	POS	Therapeutic failure; (Both criteria)
			NEG	Inconclusive; (Both criteria)
Indirect; parasitological tests	Xenodiagnosis, hemoculture	Blood trypomastigotes	POS	Therapeutic failure; (Both criteria)
			NEG	Inconclusive; (Both criteria)
Indirect; parasitological tests	PCR, qPCR	Parasite DNA	POS	Therapeutic failure; (Both criteria)
			NEG	Inconclusive; (Both criteria)
Cellular; immunology test^#	PBMC/whole blood cultures/flow cytometry	T. cruzi-specific; INF-/IL-10 producing cells	Proinflammatory	Side effect
			Balanced profile	Benefit

Conventional serological tests: CFR (complement fixation reaction), IHA (indirect hemagglutination assay), IIF (indirect immunofluorescence test), and ELISA (enzyme-linked immunosorbent assay); nonconventional serological tests: ML (complement mediated lysis), FC-ALTA (flow cytometry anti-live trypomastigotes antibodies), FC-AFEA (flow cytometry anti-fixed epimastigotes antibodies) and, FC-ATE (flow cytometry anti-live amastigote/trypomastigotes and fixed epimastigote antibodies); direct parasitological tests: fresh blood examination (FBE) and trypomastigotes concentration (buffy coat, microhematocrit, and Strout tests); indirect parasitological tests: xenodiagnosis, hemoculture, PCR, and qPCR; cellular immunology test: peripheral blood mononuclear cell and/or whole blood in vitro cultures in the presence of T. cruzi-derived antigens followed by cell surface phenotypic analysis and intracellular cytokine staining by flow cytometry. ^#Proinflammatory pattern refers to IFN- mediated immune response of NK-cells and CD8⁺ T-cells. Balanced profile refers to IL-10 modulated response by monocytes or B-cells.